In steel structure design, plate elements of a cross-section may buckle locally due to compressive stresses. The local buckling can be avoided before the limit state is achieved by limiting the width to thickness ratio of each element of a cross-section subjected to compression due to axial force, moment and shear. Thus, two types of analysis are possible on the basis of the geometric properties of a given cross section, namely Plastic analysis and Elastic analysis, for which four classes of cross sections are defined. From the given table match them appropriately:
| List-I | List-II |
|---|---|
| A.Cross section in which elements buckle locally even before reaching yield stress | 1.Class 1 (Plastic) |
| B.Cross section in which extreme fibre in compression reaches yield stress but cannot develop plastic moment of resistance | 2.Class 2 (Compact) |
| C.Cross section can develop plastic hinges and have rotation capacity required for failure | 3.Class 3 (Semi-compact) |
| D.Cross section can develop plastic moment of resistance but have inadequate plastic hinge rotation capacity | 4.Class 4 (Slender) |
- A1-A, 2-B, 3-C, 4-D
- B1-C, 2-D, 3-B, 4-ACorrect
- C1-D, 2-C, 3-A, 4-B
- D1-B, 2-A, 3-D, 4-C
Solution
Concept
Four classes of cross-sections
Step-by-step solution
1. Class 1 (plastic): forms plastic hinges with the required rotation capacity → C. 2. Class 2 (compact): reaches Mp but has inadequate rotation → D. 3. Class 3 (semi-compact): extreme fibre reaches yield, no plastic moment → B. 4. Class 4 (slender): local buckling before yield → A.
Explanation
The classes run from most ductile (1) to least (4).
Why the other options are wrong
Other options mix up the definitions.
Shortcut
1 → C, 2 → D, 3 → B, 4 → A.
Correct answer: B) 1-C, 2-D, 3-B, 4-A